Milwaukee outbreak of Legionnaire's disease sickens 14 in city

The Milwaukee Health Department is looking for the environmental source -- or sources -- of a Legionnaire's disease outbreak infecting at least 14 adults who already had underlying health conditions.

Milwaukee County has confirmed 20 cases, including 14 cases in Milwaukee, since June 1. The most recent case in Milwaukee was reported Monday.

It appears there may be two periods of exposure and illness -- the first in early June, and the second in July. About a half-dozen of the Milwaukee cases are in the same geographic area and occurred within a few days of each other in early July, said Paul Biedrzycki, director of disease control and environmental health for the Milwaukee Health Department.

No deaths have been reported, but four of the Milwaukee patients are still hospitalized, Biedrzycki said. Their conditions were not available.

The median age of those infected in the Milwaukee County cluster is 62, according to the state Department of Health Services.

Legionnaire's disease is a severe form of pneumonia caused by a bacterium known as legionella. The disease does not spread person to person. People get sick by inhaling the bacteria, which can travel through the air on contaminated water droplets or mist for up to two miles from the source. The disease takes its name from an outbreak at a Philadelphia convention of the American Legion in 1976.

The illness usually begins two to 14 days after a person is exposed to the bacteria.

Advertisement

Symptoms include chest pains, shortness of breath, nausea including vomiting and diarrhea.

Prompt treatment with antibiotics often cures Legionnaire's, but the disease can be fatal if left untreated. Typically, Legionnaire's kills 10 percent to 30 percent of those it infects, Biedrzycki said.

Possible sources for legionella may include a cooling tower on top of a building, a swimming pool where water is sprayed into the air or a decorative waterfall or fountain that is not properly disinfected. Chlorine kills the bacteria. It does not come from drinking water, Biedrzycki stressed.

Legionella naturally occurs in water that stagnates, and especially over periods of hot, humid weather, Biedrzycki said. "It's a heat-loving bacteria."

That's why businesses and schools with cooling towers on top of their buildings and those with large pools with spraying devices, should keep the water disinfected on a regular basis throughout the summer, Biedrzycki said.

"It also could be from a water source not routinely disinfected or treated. ... We're moving toward what is the common thread or source."

The area where the cluster of a half-dozen cases is concentrated is not being publicly disclosed because "this is an active investigation," Milwaukee Health Commissioner Bevan Baker said Wednesday.

"The threat to the widespread public is minimal," Baker said, adding: "We are still looking for a source. This is a real-time investigation."

While Baker said it was not a widespread threat, he acknowledged it could be an ongoing threat in the areas where cases have been reported. It's still no cause for alarm, he said.

"This is a naturally occurring bacteria and we see a handful of these cases every year," Baker said. "This is not atypical."

Asked why the health department did not notify the public of the outbreak at the same time the state reported it to area health care providers on July 10, Baker said. "We have a risk profile on when we inform. My role, and the role of the Milwaukee Health Department, is to inform but not alarm."

Milwaukee County had a total of 27 Legionnaire's cases in 2012, and 22 cases in 2011. Cases normally are seen in the hottest months of summer, in August and September.

This year's cases are unusual in number and are early, Biedrzycki said.

Biedrzycki said this is the first cluster of Legionnaire's disease in Milwaukee that he recalls investigating in at least a decade.

The first case of Legionnaire's in the city this year was reported June 1, but Biedrzycki said a cluster of cases did not become apparent until after the Fourth of July weekend.

The state Department of Health Services sent a memo to southeastern Wisconsin clinicians and infection specialists on July 10, notifying them about an increase in cases, particularly in Milwaukee County.

At the time the state sent the memo to health care providers, Milwaukee had two confirmed cases and eight suspected cases, said Sarah DeRoo, spokeswoman for the health department.

The last Legionnaire's outbreak in Milwaukee County was in March 2010, when a decorative water wall at a hospital in Cudahy was identified as the source of legionella that sickened eight people. There were no deaths.

Aurora St. Luke's South Shore in Cudahy turned off the water wall in the lobby of its facility after it was identified as the source because of high concentrations of bacteria found there.

The waterfall had been drained and cleaned every month. But water in these structures can become airborne and get into the lungs of people, including those who may have weakened immune systems.